Journal of Construction Engineering and Management

The engineering properties of compacted soils are of primary importance in fill performance. However, for economic reasons, the achievement of a given relative compaction and compaction water content has become an end in itself for field compaction control. Although the profession has developed an understanding of the relationships between properties and compaction density/water content, it has become routine practice to use some combination of precedence and code rather than desired material properties to establish compaction specifications. Because of the heavy emphasis placed on relative compaction, it is extremely important that geotechnical practitioners and earthwork contractors recognize the deviations in field density that can occur as a result of typical differences in the compaction processes and in the methods of compaction control encountered. Variations in both the field density and the laboratory-determined reference maximum dry density arise from numerous sources. A corresponding spatial variability of relative compaction should therefore be anticipated. This paper provides a comprehensive evaluation of potential problems in compaction control, and addresses the sources of field variability in relative compaction.

The rate of innovation in construction equipment is measured by using two variables over a 30-year period, 1962–92: The number of new models introduced every year and the technological life of eight earthmoving equipments are considered in this study. The findings indicate that the rate of innovation in the construction equipment industry increased in the 30-year study period. The findings also suggest that these innovations are incremental in nature, stimulated by technological advances in other industries, but primarily driven by market forces. Technological advances are not confined to the industry that produces innovations. The mapping of the interindustry flow of innovations highlights that while construction companies play a predominant role in generating their own technological innovations, they are also heavily dependent on other industries, such as the construction equipment industry for the flow of technical system innovations. As such, the continuous and incremental innovations in the construction equipment industry are bound to act as a catalyst for the generation of technological advances in the construction industry.

This is the second paper addressing the results of an investigation into the subjective nature of contract interpretation. The first paper presented the findings of the investigation which showed how contracting parties interpret contract clauses differently. This paper reports the testing of a revised Canadian Standard Lump Sum Contract against its predecessor. The intent of this study was to measure the improvement of the wording-not in legal terms, but in terms of what the potential signatory to, or administrator of, the contract understood. The measure, as in the previous study, was the extent to which there was a “meeting of the minds” in interpretation of who was bearing particular risks. Unlike many contracts used today that are written by the owner or its representative, this standard form contract was drafted by a committee representing contractors and consultants, but not owners. An interesting observation was that owners were generally prepared to assume more risk than they perceived was being allocated to them while contractors wanted less risk.

A methodology to analyze construction firms' long-term strategies is described. This methodology provides a systematic approach to study and analyze external and internal scenarios for a construction firm doing strategic planning. A conceptual model that is a simplified model of the variables and interactions present in the analysis of strategic decisions in the construction industry is built. An analytical model designed to predict the impact of strategic decisions supports the analysis process by integrating expert knowledge and assessments of the strategic planning team into a mathematical model. This model uses concepts of cross-impact analysis and probabilistic inference to capture risks and uncertainties present in the strategic scenarios. Strategies for long-term company development such as marketing programs to emergent markets, systems to implement total quality, etc., can be evaluated using criteria selected by company management. The model allows management to test different combinations of company long-term strategies and predict expected sales, market share, or other measures of company performance. The case of a Chilean construction company is used to illustrate the methodology.

The paper describes an approach developed to estimate construction productivity for concrete formwork tasks. The system utilizes artificial neural networks, historical information, and input from experienced superintendents employed by a leading construction general contractor. It also summarizes a study undertaken to determine factors that affect labor productivity, the survey conducted to collect relevant data, and the design, training, and implementation of artificial neural networks at the participating company. A number of alternative neural network structures were investigated, the adopted one was a three-layered network with a fuzzy output structure. It was found that this structure provided the most suitable model since much of the input was subjective. A brief overview of the computer implementations and the overall experience with the system development is also provided. The method was compared to an existing statistical model developed by the same contractor and was found to improve the quality of the estimates attained. A case study conducted in the context of a workshop with senior estimators is also presented.

It has long been believed that improving project integration directly improves project performance. There has been a lack of quantitative research to directly support or negate this belief. This paper presents a method for approximating project integration, and demonstrates the impact of improved interaction on project performance. An earlier work developed a method for measuring an individual project's “degree of interaction” (DOI). Degree of interaction scores are calculated and compared for 38 projects, divided into traditional and alternative project approaches. The alternative projects have significantly higher average DOI scores than do traditional projects, indicating that they provide better opportunities for interaction. Project performance of alternative projects is better than that of traditional projects. The following four indicators of project performance are measured: cost growth, schedule growth, number of contract modifications, and modifications due to design deficiencies. The impact of improved interaction on objective performance measures is validated by studying 209 completed projects.

An information classification system in construction management is related to specifications, bills of quantities, network analysis, and cost estimating. A construction information classification system (CICS) provides a common method of improving coordination of information for design, construction, and management. The Masterformat and CI/SfB systems are widely used for an information system, but the existing systems can be applied to construction in civil engineering only with great difficulty. The present study analyzes adaptability as an information classification system for civil works through a comparative study of the Masterformat, SfB, CI/SfB, and CESMM systems and the ISO system, which is in development. This study suggests that a basic skeleton of CICS for civil works keeps a faceted system, and the classified facets consist of facility, space, element, construction operation, and resource.

This paper investigates “concurrent construction” and its potential application in life cycle management of capital projects. The construction industry is under pressure to reduce project delivery times and costs despite increased uncertainties, ambiguities, and complexities that surround today's projects. Concurrent construction may well hold the key to success on this front. Concurrent construction is based on integrating all project phases into a single phase. It starts with the definition of a product model and division of the project into major parts or systems accordingly. Each part or system is entrusted to a team consisting of members drawn from the relevant disciplines as well as the contractor. The delivery of a specific part is carried out by the relevant team in an integrated fashion in a single phase. While the potential benefits of concurrent construction are beyond doubt, current contractual, organizational, and work method barriers militate against realizing these. However, there are workable solutions to these problems. This paper covers examples of approaches that could overcome these barriers.

This paper presents a case study that assesses three asphalt concrete paving specifications currently in use in various areas of the country. The primary question addressed is how specifications relate quality characteristics to payment for performance. The study indicates that there is little or no consistency with respect to what different highway agencies consider as quality and how quality is paid for through the use of payment factors. It is clear that the key to good specifications is research that identifies and quantifies the relationships that pay factor calculations are based upon. After settling on the quality characteristics, a major concern that must be addressed is determining what test method best represents the characteristic, and can these characteristics be determined at the time of construction. It is clear that there is considerable work still to be done in developing good specifications that ensure a quality product and are equitable to both the owner and contractor.

Actual tunnel advance rates from the Outfall Tunnel of the Boston Harbor Cleanup Project are analyzed. It is shown that states of work and nonwork for the tunnel boring machine can be modeled with a Markov chain. A general probabilistic approach is proposed for developing the cumulative distribution function (CDF) of the total length that can be tunneled in a given time frame. Simulation models are developed to verify the results of the analytical model and also to simulate the distribution for the time necessary to tunnel a certain length (in this case the remainder of the tunnel). The validity of the predictive model is verified using the data from the completed project. The proposed approach may be used for relatively long tunnels with durations extending over several months where the tunneling has already begun and sufficient progress data have been collected. The data from progress up to a certain date may be used for forecasting the length of tunnel that can be constructed in a specified duration.

A general mathematical formulation is presented for the scheduling of construction projects and is applied to the problem of highway construction scheduling. Repetitive and nonrepetitive tasks, work continuity constraints, multiple-crew strategies, and the effects of varying job conditions on the performance of a crew can be modeled. An optimization formulation is presented for the construction project scheduling problem, with the goal of minimizing the direct construction cost. The nonlinear optimization is then solved by the neural dynamics model developed recently by Adeli and Park. For any given construction duration, the model yields the optimum construction schedule for minimum construction cost automatically. By varying the construction duration, one can solve the cost-duration trade-off problem and obtain the global optimum schedule and the corresponding minimum construction cost. The new construction scheduling model provides the capabilities of both the critical path method (CPM) and linear scheduling method (LSM) approaches. In addition, it provides features desirable for repetitive projects, such as highway construction, and allows schedulers greater flexibility. It is particularly suitable for studying the effects of change order on the construction cost. This research provides the mathematical foundation for development of a new generation of more general, flexible, and accurate construction scheduling systems.